Plug adapter with safety switch

ABSTRACT

This invention is a three-wire grounding electric adapter that is comprised of a body, a first end and a second end wherein said first end has a vertical planar face capable of detachably engaging a 3-wire electric cord, said second end has a second vertical planar face. The body has a switch that is mounted on said body for permitting said adapter to complete, or disrupt positive electrical current from electrical receptacle to an electric device of at least two electric contact blades. The blades are fixedly mounted in said second end and extending outwardly from said second vertical planar face for engaging in an electric outlet. A security screw for securing at least one blade of an electric device plug into said adapter locking at least one blade into the adapter.

FIELD OF THE INVENTION

[0001] This invention relates to electrical adapters, and moreparticularly to improved 3-wire, grounding type adapter with an on/offswitch and a locking mechanism.

BACKGROUND OF THE INVENTION

[0002] The hazard of operating ungrounded electrical devices is wellrecognized. As a result, the Underwriter's Laboratories, Inc. and manyelectrical codes long have required that all portable electrical toolsbe equipped with suitable grounding means.

[0003] The “Underwriter's” have required that plugs for electricaldevices be equipped with a three-prong plug for insertion into a 3-wirereceptacle.

[0004] Over the years, a variety of three-prong plugs have beenpatented, see U.S. Pat. Nos. 2,323,736; 2,922,134; 2,986,718; 2,876,426;3,134,631; 3,178,667; 3,219,962; and 2,984,808.

[0005] As disclosed in U.S. Pat. No. 2,323,736, there is shown athree-prong plug in which the ground prong is capable of being retractedfrom a position of use, depending on whether or not a 3-wire electricaloutlet is encountered.

[0006] When retracted for use with a 2-wire outlet, however, this leavesthe electrical device with which the plug is associated ungrounded. U.S.Pat. No. 2,984,808 discloses another three-prong convertible plug inwhich the ground plug can be pivoted into the use position or not asdesired. A “pig-tail” connection is provided on the plug, and inconnection with the ground, for connection to the ground screw of a2-wire receptacle. Another three-prong plug in which a pivotable groundprong is provided is disclosed in U.S. Pat. No. 2,986,718. A “pig-tail”is provided which connects to the ground and which is provided with aconnection at the other end for connection to the ground screw in caseof use with a 2-wire electrical outlet.

[0007] U.S. Pat. Nos. 2,876,426 and 2,922,134 disclose electricalconnecting plugs in which a pivotable grounding element is provided. Theground prong on encountering the 2-wire outlet is pivoted so that thefinger portion of the grounding prong is out of position so that theconnecting plug can be used. In U.S. Pat. No. 2,876,426, the other endof the pivoted prong is constructed so that on the prong being pivoted,it is in contact with the grounded receptacle plate and, in turn,grounds the electrical device.

[0008] U.S. Pat. No. 3,134,631 discloses another three-prong electricalplug in which the ground prong is pivotable out of position in case theplug is used with a 2-wire electrical outlet. The ground prong isprovided with a groove adjacent its free end for insertion of a groundwire which in turn can be connected to a ground lead in the electricaloutlet. A further electrical plug which is provided a pivotable prong isdisclosed in U.S. Pat. No. 3,178,667. When a 2-wire outlet isencountered, the pivotable ground prong therein is resiliently urgedagainst the faceplate of the receptacle to establish a ground, therebyreducing the possibility of a shock being transmitted to the user of anelectrical device.

[0009] U.S. Pat. No. 3,219,962 discloses an electrical connector plug inwhich a pivotable ground prong is provided and which is disclosed foruse with either a 2 or 3-wire receptacle. The ground plug is biased toits operative position.

[0010] Note also U.S. Pat. No. 5,171,155, which teaches the use ofsafety locks for electrical appliances.

[0011] While all of the electrical plugs as above disclosed are suitableto a degree, their use does involve certain problems and disadvantages.None of the referenced adapters uses a switch with a 3-prong groundingplug and a security screw for attaching a plug of an electric cord to apower on/off switching device.

SUMMARY OF THE INVENTION

[0012] A three-wire grounding electric adapter comprising:

[0013] (a) a body comprising a first end and a second end wherein thefirst end has a vertical planar face capable of detachably engaging a3-wire electric cord, and the second end has a second vertical planarface;

[0014] (b) a switch mounted on the body for permitting the adapter tocomplete or disrupt positive electrical current from electricalreceptacle to an electric device; provided a pivotable prong isdisclosed in U.S. Pat. No. 3,178,667. When a 2-wire outlet isencountered, the pivotable ground prong therein is resiliently urgedagainst the faceplate of the receptacle to establish a ground, therebyreducing the possibility of a shock being transmitted to the user of anelectrical device.

[0015] U.S. Pat. No. 3,219,962 discloses an electrical connector plug inwhich a pivotable ground prong is provided and which is disclosed foruse with either a 2 or 3-wire receptacle. The ground plug is biased toits operative position.

[0016] Note also U.S. Pat. No. 5,171,155, which teaches the use ofsafety locks for electrical appliances.

[0017] While all of the electrical plugs as above disclosed are suitableto a degree, their use does involve certain problems and disadvantages.None of the referenced adapters uses a switch with a 3-prong groundingplug and a security screw for attaching an electric cord to an outletand switched on/off power device.

SUMMARY OF THE INVENTION

[0018] A three-wire grounding electric adapter comprising:

[0019] (a) a body comprising a first end and a second end wherein thefirst end has a vertical planar face capable of detachably engaging a3-wire electric cord, and the second end has a second vertical planarface;

[0020] (b) a switch mounted on the body for permitting the adapter tocomplete or disrupt positive electrical current from electricalreceptacle to an electric device;

[0021] (c) at least two electric contact blades fixedly mounted in thesecond end and extending outwardly from the second vertical planar facefor engaging in an electric outlet; and

[0022] (d) a security screw for securing at least one blade of anelectric device plug into the adapter locking at least one blade intothe adapter.

BRIEF DESCRIPTION OF THE DRAWING

[0023] The invention will be best understood in the following detaileddescription of a preferred embodiment thereof, taken in connection withthe appended drawings in which:

[0024]FIG. 1 is a perspective view of an adapter in accordance with theinvention.

[0025]FIG. 2 is a view of the security screw.

[0026]FIG. 3 is an end view of the invention with the switch on the topof the body of the adapter.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENTS

[0027] The present invention is designed to have a switching mechanismand a secure locking mechanism to prevent use of electrical devicesincluding home audio/video equipment, power tools and the like whichhave electrical cords. The adapter is usable in electrical plugreceptacles with three slots to receive a standard U.S. plug (of eithertwo prong or three prong ground design) made of an insulating materialsuch as a plastic. The plug of any electrical device is inserted intothe adapter and a locking pin is secured to the blade of the plug byrotating a locking screw with a security key tool having a unique top. Aconvenient tie strap is attached to the adapter to secure the adapter tothe electrical cord of an appliance that the user wishes to lock up. Theadapter is designed as a locking mechanism for the plug of an electricalreceptacle for any electrical device's plug and at the other end a setof electrical prongs (plug) which may be subsequently inserted into anelectrical outlet receptacle. The adapter is also additionally designedto contain an electronically keyed remote on/off switch or remote switchwhich allows power flow to be controlled. Miniature tumbler switch lockswhich can be used within the scope of this invention and include.Miniature carrier transmitters can be used in the scope of thisinvention such as Levitons' hand held controller, which permits wirelesscontrol of the cord through a transceiver catalog number 6314-W.

[0028] Turning now to the drawing, there is shown herein in FIG. 1 aself-grounding electric adapter 10 having three cavities 12, 14, 16 forreceiving the blades of a 3-wire electric conductor cord connected to anelectrical device such as a portable hand tool. The electric adapter 10comprises a body 18 having a first end 20 with a planar face capable ofdetachably mating with a three prong plug from an electrical device,such as a power sander.

[0029] Adapter body 18 has a second end 22 with prongs 24, 26 and 28suitable for insertion into either a two or three wire electricaloutlet.

[0030] The shapes of cavities 12, 14 and 16 need be of a shape capableof receiving the blade. The main consideration is that the matingsurfaces be complementary so as to provide a suitable detachablecombination. In general, the mating surfaces will fit together, male andfemale; however, this mating can take various configurations.

[0031]FIG. 2 shows the unique locking security screw 30 as used in acavity 32 of FIG. 1, which enables the security screw 32 to pass throughthe blade of the inserted electric cord and lock the cord blade into thecavity. The screw 32, shown in detail in FIG. 2 has a head 34, a shaft36 and a tab 38. In the preferred embodiment, a security screw tab 38which fits into a security screw guide channel to insure a secure lockof the screw 32 onto the blade. Head 34 has a top 40 which has anindentation or cavity 42 into which a unique security key tool 13 havingthe identical shape of the cavity is inserted. The security key tool canbe like an allen wrench, but have a face design that is either starshaped, triangle shaped, pentagonal shaped, or in the shape of anoctagon, squiggle or spiral.

[0032]FIG. 3 shows an isometric view of the electric adapter whereincavities 12, 14 and 18 receive the plug from the electric device. Strap44 can be used to hold the adapter to the cord from the electric device.FIG. 3 shows also the cavity 32 holding security screw 32. Prongs 24, 26and 28 provide the electrical connection to the wall outlet.

[0033] The switch 46 can be a manual switch or an electronic switch inthe device which has on and off positions.

[0034] The body 18 can be made of rubber or another insulating material,for example, plastic material. These materials for the casing can bechosen to provide a relatively flexible plug body, or one which is morerigid. A flexible plug body is the most preferred. Such a body can beprovided through various conventional molding techniques, such asinjection molding.

[0035] As many different embodiments of this invention will now haveoccurred to those skilled in the art, it is to be understood that thespecific embodiments of the invention as presented herein are intendedby way of illustration only and are not limiting on the invention, butthat the limitations thereon can be determined only from the appendedclaims.

What is claimed is:
 1. A three-wire grounding electric adaptercomprising: (a) a body comprising a first end and a second end whereinsaid first end has a vertical planar face capable of detachably engaginga 3-wire electric cord, said second end has a second vertical planarface; (b) a switch mounted on said body for permitting said adapter tocomplete or disrupt positive electrical current from electricalreceptacle to an electric device; (c) at least two electric contactblades fixedly mounted in said second end and extending outwardly fromsaid second vertical planar face for engaging in an electric outlet; (d)a security screw for securing at least one blade of an electric deviceplug into said adapter locking at least one blade into the adapter. 2.The adapter of claim 1, wherein said security screw has a head, a shaftand a tab for lockably engaging at least one blade from a cord of anelectric device, and wherein said head has an indentation for receivingthe blade of a security key tool having a shape which is selected fromthe group: star, triangle, pentagon, octagon, a squiggle, and spiral. 3.The adapter of claim 1, further comprising a strap secured to saidcasing for restraining the cord from the electrical device.
 4. Athree-wire grounding electric adapter comprising: (a) a body comprisinga first end and a second end wherein said first end has a verticalplanar face capable of detachably engaging a 3-wire electric cord, saidsecond end has a second vertical planar face; (b) an electronicallyactuated switch mounted on said body for permitting said adapter tocomplete or disrupt positive electrical current from electricalreceptacle to an electric device; (c) at least two electric contactblades fixedly mounted in said second end and extending outwardly fromsaid second vertical planar face for engaging in an electric outlet; (d)a security screw for securing at least one blade of an electric deviceplug into said adapter locking at least one blade into the adapter. (e)a power source connected to said electronically actuated switch
 5. Theadapter of claim 4, wherein said power source is a battery.
 6. Theadapter of claim 4 further comprising a strap secured to said casing forrestraining the cord from the electrical device.
 7. The adapter of claim4 further comprising the electronic on/off switching device by a “keyed”mechanism.
 8. The adapter of claim 4 further comprising the electronicon/off switching device by a remote controlled on/off device.